Apparatus for teaching sewing

ABSTRACT

A METHOD AND APPARATUS FOR TRAINING SEWING MACHINE OPERATORS AND FOR EVALUATING THEIR PERFORMANCE INCLUDES PAPER SEWING EXERCISES OF INCREASING DIFFICULTY AND SENSING APPARATUS FOR AUTOMATICALLY MONITORING THE EXERCISE TO DETECT AND RECORD ALL ERRORS MADE BY THE TRAINEE. THE APPARATUS AUTOMATICALLY RECORDS THE NUMBER OF ERRORS MADE, THE LOCATION IN THE EXERCISE OF EACH ERROR AND THE RATE AT WHICH EACH SIGNIFICANT PORTION OF THE EXERCISE IS PERFORMED. BY ANALYZING THE NUMBER, LOCATION, AND FREQUENCY OF VARIOUS TYPES OF ERRORS AND THE TIME REQUIRED TO PERFORM EACH EXERCISE, THE PRESENT METHOD AND APPARATUS PERMITS AN INSTRUCTOR TO GUIDE AN OPERATOR&#39;&#39;S TRAINING AND EVALUATE A TRAINEE&#39;&#39;S PERFORMANCE AND ABILITIES.

Oct. 5, 1971 R. M. GREEN 3,609,88!

APPARATUS FOR TEACHING SEWING Filed Dec. 29, 1969 2 Sheets-Sheet l 36 SOLENOID(ERRORS) 2 3 SOLENOID 74 15v 50 COUNTE BM) 22 I6 F/ G. PU-2 l4a 12 IZ *XJ m'vm '1 rm ROBE RT M. GREEN 1971 R. M. GREEN 3,609,385

APPARATUS FOR TEACHING SEWING Filed Dec. 29, 1969 2 Sheets-Sheet 3 PU- 2 PU-3 PU-3 F/G.3 H64 H65 F/6-6 ROBERT M. GREEN United States Patent fice 3,609,881 APPARATUS FOR TEACHING SEWING Robert M. Green, Woodhury, N.Y., assignor to Industrial Teaching Systems Corporation, New York, NY. Filed Dec. 29, 1969, Ser. No. 888,611 Int. Cl. G091) 25/02 US. CI. 3513 Claims ABSTRACT OF THE DISCLOSURE A method and apparatus for training sewing machine operators and for evaluating their performance includes paper sewing exercises of increasing difiiculty and sensing apparatus for automatically monitoring the exercise to detect and record all errors made by the trainee. The apparatus automatically records the number of errors made, the location in the exercise of each error and the rate at which each significant portion of the exercise is performed. By analyzing the number, location, and frequency of various types of errors and the time required to perform each exercise, the present method and apparatus permits an instructor to guide an operators training and evaluate a trainees performance and abilities.

This invention relates generally to a method and apparatus for training and testing sewing machine operators and more specifically to a method and apparatus for conducting paper sewing exercises and evaluating such exercises in a quantitative manner.

In the training of commercial sewing machine operators, it is common practice to conduct a series of paper drills before permitting an operator to commence actual work. Such drills are designed to teach an operator basic machine control and to prepare her for specific sewing jobs. In the conventional paper drill, the trainee-operator is provided with paper exercise sheets including guidelines defining a desired stitching sequence and is instructed to stitch along the guidelines. The evaluation of these exercises by supervisory personnel has heretobefore been on a strictly qualitative basis. A supervisior-trainer normally examines a series of exercises and subjectively judges in a very informal manner the quality of the end product of a trainees work to determine whether the trainee is prepared to advance to a more difiicult exercise or possibly to an actual work assignment.

The conventional method of conducting and evaluating pattern drills has numerous disadvantages which are overcome by the present invention.

In the conventional method, the supervisor reviews r only the final work product and does not review the manner in which the work was actually done. For example, the supervisor has no record of the time required by the trainee to complete each phase of the exercise. The time factor is actually an important component in the evaluation of sewing exercises.

The amount of relevant and useful information which a supervisor can obtain from a qualitative review of a trainees exercise is very limited. Basically, even the most experienced supervisor can merely determine very subjectively whether the trainee is prepared to advance to a higher level of work. Applicant has determined that detailed and systematic analysis of selected sewing exercises can provide a substantial amount of additional useful information with respect to a trainees performance, abilities, and potential for improvement. For example, such detailed systematic analysis can isolate and identify an operators inherent abilities and disabilities, permitting trainees capable of handling diflicult procedures to be trained in such procedures while those potential is limited can be assigned to simpler work.

Further, in reviewing paper exercises, a supervisors 3,609,881 Patented Oct. 5., 1971 judgement is likely to be affected by personal prejudices or other extraneous factors. Objective examination and analysis of a trainees work according to predetermined standards eliminates the personal bias of the supervisor and permits each trainee to be judged on a purely objective and uniform standard. It also permits training exercises to be supervised by relatively unskilled personnel.

Additionally, the informal and subjective use of paper drills in the prior art created no permanent record of an operators training and ability, making reassignment of work and retraining time consuming and difficult. In the present system, a permanent record is kept of each trainees exercise experience and performance. These records can be referred to periodically as needed without conducting a new series of drills.

It is an object of the present invention to train sewing machine operators and evaluate their performance in a quantitative manner while teaching basic industrial sewing machine control.

A further object of the present invention is to evaluate the performance and abilities of a sewing machine operator according to significant criteria not heretobefore employed in such evaluation.

It is a still further object of the present invention to permit sewing exercises to be conducted and supervised by relatively unskilled personnel and evaluated by such personnel according to predetermined objective standards.

In accordance with a preferred embodiment demonstrating additional objects and features of the present invention, a trainee is provided with a series of exercise sheets having one or more guidelines thereon defining a desired stitching objective. The trainees sewing machine is provided with sensing means for automatically determing when the operator is stitching along the guideline and when the operator is stitching away from the guidelineeach time the trainee stitches away from the guideline being characterized as an error. The apparatus further includes recording means for creating a record of the number of errors, the location of each error in the exercise, and the length of time required by the operator to perform each aspect of the exercise. By comparing the individual trainees error record with predetermined performance standards, a trainees performance is evaluated and the trainees ability to perform specific types of work is determined.

Further objects, features and advantages of the present invention will be apparent from the following detailed description of a presently preferred, but nonetheless illustrative embodiment thereof, when considered in connection with the attached drawings, wherein:

FIG. 1 is a diagrammatic representation of the basic system including a portion of a typical sewing exercise sheet, a specially adapted sewing machine presser foot and an appropriate sensing and recording circuit;

FIG. 2 shows a selected portion of a typical sewing exercise sheet and a segment of a typical strip recording produced by the system;

FIGS. 3-6 show examples of various bench mark configurations with the corresponding pulse pattern they produce;

FIG. 7 is an exploded view of the specially adapted presser foot; and

FIG. 8 is a bottom view of the presesr foot.

Referring now to the drawings, FIG. 1 shows the three basic elements of a presently preferred embodiment of the invention, including a portion of a typical sewing exercise sheet 10 having sewing guidelines 12a, 12b thereon, a specially adapted presser foot 16 for sensing when the trainee is stitching on the guidelines and a sensing and recording circuit 22 for creating a permanent tape record of the training session. As the trainee performs each exercise, each error made (an error occurs each time the trainee stitches away from the guideline) is recorded along with time markings and an indication of the trainees position along the exercise. The error record is later analyzed in accordance with predetermined performance standards relating to the number of errors reasonably to be expected in various segments of the exercise and the time required for completion of the segments.

The exercise sheet is of paper or other non-electro-conductive material and the guidelines 12a, 12b are printed with electro-conductive ink. Guidelines 12a, 12b are solid lines although they are shown in outline only in the drawings for convenience. The exercise sheet also includes a series of bench marks 14a, 14b separating the guideline into regions of special interest. In the simple exercise of sheet 10, guidelines 12a, 12b are merely straight lines and bench mark patterns 14a, 14b mark the start of the lines. A series of exercise sheets will normally be employed during any given training exercise; first to teach basic control of the sewing machine and then to teach various stitching patterns from the simplest to the most complex. The simple exercises such as the separate straight line sections 12a, 12b of sheet 10 are used to teach starting and stopping the machine at specific points. In more complex exercises, a single line tracing a complicated pattern, including curves, zig-zags and straight sections may be employed. Suitable pattern designs are dependent on the particular job for which the operator is being trained, the level of ability of the trainee and other similar factors. Whatever the complexity of the exercise, the trainee is instructed to stitch along the guideline from a starting point to an end point, just as she would were such a line of stitching required in an actual job.

The specially prepared presser foot 16 (see also FIGS. 7 and 8) is adapted to be mounted on an industrial sewing machine. Generally, the presser foot of a sewing machine has a substantially flat undersurface 18 with an upwardly curving forward edge 20 including a slot 24. The foot is mounted on the sewing machine by a liftable support of a type well known in the art with the sewing needle passing through slot 24. To sew, the foot is raised and the goods to be sewn are positioned on the work surface. The foot is then lowered onto the work to maintain the work flat and steady during the sewing process and to cooperate with a feed dog beneath the work surface to advance the goods.

To sense when the trainee is on the guideline, presser foot 16 includes a series of electrical probes exposed on its lower surface which make contact with the electroconductive guidelines 12a, 12b and the electro-conductive bench marks 14a, 14b. As seen in FIGS. 1 and 8, foot 16 includes a primary guideline sensing probe PU-l and a pair of ground contacts 28 lateral of the guideline sensing probe. The ground contacts extend forward from a bus bar 26 and probe PU-l passes over bus 26 and is resilient so as to bear down on bus 26, shorting probe PU1 to ground when the foot is not in use. When the foot is lowered, the depending tip of probe PU1 contacts the paper and probe PU-l is raised in an obvious manner, breaking the short to ground. The significance of the arrangement will be apparent later.

Adjacent the guideline sensing probe and the ground probes, presser foot 16 is equipped with a pair of benchmark sensing contacts P.U2, PU-3 located forward and rearward of one another with a selected spacing therebetween. These contacts detect where the trainee is in the exercise by providing a unique indication in circuit 22 when each bench mark is passed. The operation of the sensing network 22 in conjunction with probes PU-l, PU-Z and PU-3 and the electro-conductive guidelines and bench marks is as follows:

In the electronic sensing and recording circuit 22, the line voltage is applied to terminals 30a, 30b connected across the primary winding of transformer 32. The secondary winding of the transformer is connected across full-wave rectifier 34. The rectifier functions to derive a potential on conductor 36 which is positive relative to the potential on conductor 38. The latter conductor is grounded and consequently conductor 36 serves as the positive power supply for the circuit. The voltage on the conductor is full-wave rectified, and thus varies between ground voltage and a maximum potential at a cycleper-second rate.

When the presser foot is raised, pick-up contact PU-l is shorted to ground as described above. The emitter of transistor T1 is held at ground potential through resistor 44. The base of transistor T1 is at a positive potential as a result of current flow from bus 36 through resistors 40 and 42 to the grounded PU-l contact. However, resistor 40 is much greater in magnitude than resistor 42 and the potential at the base of transistor T1 is insuflicient for turning the transistor on. The emitter of transistor T1, and thus the control gate of SCR switch 60 are held at ground potential.

When the presser foot is lowered, the ground potential applied directly to contact PU-l by the internal presser foot connection is removed. Instead of a fixed ground potential appearing on this contact, the contact is grounded only if it engages the electro-conductive pattern track 12 on the exercise sheet which is maintained at ground potential by ground contacts 28 (see FIGS. 1 and 8) on the presser foot. As long as the operator is on course contact PU-l is grounded and transistor T1 remains off.

As soon as the operator goes otf course the base of transistor T1 is no longer connected to ground through resistor 42. Instead, current flows from bus 36 through resistor 40 and the base-emitter junction of transistor T1. The current divides between resistor 44 in one branch; and resistors 46 and 48 in another, These resistors have magnitudes such that the potential at the junction of resistors 46 and '48 is suflicient to fire SCR switch 60.

When the SCR switch fires, current flows from bus 36 through both counter 50 and the winding of error solenoid 54, and then through the SCR switch to ground. When the current first flows the counter is incremented to indicate that another mistake has occurred. At the same time the error solenoid operates moving a recording style (see FIG. 2) from its rest position to its error" position thus recording the error.

The SCR switch does not remain on continuously even if contact PU-l remains ungrounded and transistor T1 remains conducting. Since the efiective power supply for the SCR is a full-wave rectified signal, the potential on bus 36 goes to ground 120 times per second. Each time that the bus potential goes to ground, the SCR turns oif. Capacitor 56 is connected across the SCR, as is known in the art, in order to insure that the SCR turns off. Immediately after the SCR turns ofl? the potential on bus 36 starts to rise. If the operator is still off course and transistor T1 is still conducting, the positive potential at the control gate of the SCR is still high enough to trigger it on once again.

It is apparent that the SCR turns on and off at a rate of 120 times per second for as long as the operator mains oif course. Although the SCR switches on and off at a rapid rate, counter 50 is incremented only pnce. The counter is of the conventional type in which the input signal must be absent for a minimum time interval before the counter will be incremented once again by the signal.- This time interval is greater than the off time of the SCR and consequently counter 50 is incremented only once for the sequential on-an-oif switching of SCR switch 60. Similarly, solenoid 54 remains energized even when the potential of bus 36 goes to ground because the solenoid similarly has a release time sufiicient to maintain it operated between successive energization.

Diode 52 is provided to short the solenoid winding when the SCR turns oif. The use of such a diode is well known to those skilled in the art; it functions to prevent an excessive voltage from developing at the anode of the SCR when current through the switch ceases.

The SCR is purposely turned off periodically (120 times per second). When contact PUI becomes ungrounded the SCR control gate rises in potential and the SCR turns on. When contact PU-l is grounded once again, the control gate of the SCR returns to ground but this does not turn the SCR off since once the SCR fires the control gate loses control. The SCR is caused to turn off by using an unfiltered power supply. The SCR remains otf, however, only if the operator gets back on course.

By alternately activating and deactivating solenoid 54, the on course sensing circuit controls styles 82 in FIG. 2 and traces an error line in column B of strip 86. The error line shows a pulse each time an error occurs with the pulse width being proportioned to the duration of the error. Strip recorders including solenoids 88, 54 and 76 and corresponding markers 84, 82 and 80 are well known in the art and will not be described herein in detail.

A similar circuit is provided for controlling the energization of bench mark solenoid 76 when contacts PU2 and PU3 are both grounded by segments of the bench mark conducting pattern 14a, 14b on the paper through ground contacts on the pressure foot. At such a time, transistor T3 conducts (as will be described below) and current flows through resistors 68 and 72. The potential at the junction of the resistors appears on the control gate of SCR switch 70 and the SCR turns on. Current flows through the winding of solenoid 76 and the switch. Each time that the potential on bus 36 returns to ground, SCR switch 70 turns off. Capacitor 72 further insures that the SCR turns off. Diode 74 is provided to short the winding of solenoid 76 at this time. Again, the solenoid is of the slow-release type so that it does not de-energize until SCR switch 70 finally turns off for the last time in the sequence of on-and-otf switching. The SCR turns oif for the last time, that is, it is not triggered to conduction once again, when at least one of contacts PU2 and PU3 is no longer grounded and the control gate of the SCR is held at ground potential through resistor 72.

Only a single transistor T1 is required in the circuit to trigger SCR switch 60 when contact PU1 is ungrounded. It will be recalled, however, that the bench mark solenoid is to be operated only When the two contacts PU2 and PU3 are both simultaneously grounded. A pair of transistors T2 and T3 is provided for controlling the triggering of SCR switch 70 only when the two respective pick-up contacts are grounded.

The emitter of transistor T3 is connected to the collector of transistor T2. Consequently, transistor T3 cannot conduct unless transistor T2 conducts. As long as contact PU2 is ungrounded, the base of transistor T2 is held at the potential of bus 36 through resistor 58. Since the emitter of the transistor is connected directly to the bus, the base and emitter potentials are equal and the emitterbase junction is not forward biased. As soon as contact PU2 is grounded, however, current flows from bus 36 through resistors 58 and 62 to ground. The voltage drop across resistor 58 results in a base potential which is less than the emitter potential. With the emitter-base junction forward biased, transistor T2 can conduct.

However, collector current from transistor T2 cannot flow unless contact PU3 is also grounded. If this contact is not grounded, the base potential of transistor T3 is the same as the collector potential of transistor T2 since no current flows through resistor 64. The emitter potential of transistor T3 is the same as the collector potential transistor T2. Without an emitter-base forward bias, tr nsistor T3 cannot conduct and no current flows from the collector of transistor T2.

Only if pick-up contact PU3 is grounded at the same time that pick-up contact PU2 is grounded does current flow from the collector of transistor T2 through resistors 64 and 66 to ground. The voltage drop across resistor 64 causes the base potential of transistor T3 to be lower than the emitter potential. Consequently, the emitter base junction is forward biased and current from the collector of transistor T2 flows through the emitter-collector circuit of transistor T3 and through resistors 68 and 72 to ground. The potential at the junction of the resistors rises above ground to trigger SCR switch 70. As long as both of pickup contacts PU2 and PU3 are connected to ground through the bench mark conducting strip on the paper, SCR switch 70 is continuously switched on and otf at a rate of 120 times per second. Solenoid 76 remains energizled for as long as the on-and-otf switching continues at this rate, and the energization of the solenoid is an indication that the operator is working at a point on the pattern adjacent to a bench mark. The particular sequence of energization of the solenoid uniquely indicates the particular bench mark being passed as described in detail below.

Referring to FIG. 2, the bench mark circuit produces a selected pulse code in column C of recording strip 86 depending on the configuration of bench marks on the exercise sheet. Sample bench marks and the corresponding pulse codes are shown in FIGS. 3-6. The dotted line through the bench marks in each of these figures shows the path of the bench mark pick-ups PU2, PU3 as they pass over the bench mark pattern. The points PU2, PU3 marked in FIGS. 3-7 represent the location of the bench mark pick-ups when the recorder records the upside of the first pulse in each pulse series. Note that the spacing between the bench mark pick-ups as compared to the relative length along the pick-up path of each bench mark in the bench mark series and the distance between bench marks determines the pulse code pattern produced.

The simple bench mark pattern 100 of FIG. 3 produces the simple one pulse code 90 is an obvious manner. The double bench mark pattern 102 of FIG. 4 produces a double pulse code 92 as follows: when both probes PU2 and PU3 are in contact with mark 102a they are both grounded through ground contacts 28 and solenoid 76 is activated driving stylus to its raised position. When probe PU3 passes off mark 102a the solenoid is deenergized and arm 80 moves back to its rest position creating the downward side of the first pulse of series 92. When probe PU3 becomes grounded through bench mark 102b (contact PU2 remaining grounded through bench mark 1020) the solenoid 76 is re-energized and creates the upside of the second pulse of series 92. When contact PU3 passes mark 10211, the solenoid is de-energized creating the downside of the second pulse of series 92.

The pattern 94 created by the bench mark arrangement of FIG. 5 is similar to FIG. 4, except that mark 104a has a greater length than mark 102a thereby creat ing a longer first pulse in series 94.

By tracing the consecutive activation and deactivation of solenoid 76 as probes PU2 and PU3 pass downward along the bench marks of FIG. 6, it will be seen that pulse code 96 is generated.

The bench mark system thus provides a unique indication in column C of strip 86 (in terms of the number of pulses and width of pulses) for each bench mark notation along the guideline permitting the instructor reviewing the tape of a training exercise to correlate the trainees progress in the exercise with errors made. It will be apparent that the actual width of the pulses of each pulse code will depend in part on the rate at which the operator does the exercise, since the strip recorder moves at substantially a constant rate and the length of time the solenoid is activated depends on the length of time contacts PU2, PU3 are both in contact with a bench mark. The width of the pulse will thus be dependent on the speed of the sewing machine and other factors. However, any given series of bench marks always produces a specific number of pulses and, in practice, an operators rate of Work does not change substantially in a short space so that the relative width of the pulses in each 7 pulse code series will correspond approximately to the relative width of the bench marks.

It is to be understood that the apparatus shown in the figures employs one of numerous possible sensing systems which may be employed without departing from the spirit or scope of the present invention. For example, a light transmission system may be employed wherein the presser foot is equipped with an appropriate illuminating device and a photoelectric sensor is located below sheet 10. Other sensing arrangements will be obvious to those skilled in the art.

As seen in FIG. 2, the recording apparatus includes solenoid 88 controlled by a clock mechanism (not shown) of a type which is well known in the art. Solenoid 88 controls stylus arm 84 which generates a time line in column A of strip 86 which permits an instructor to correlate the error and bench mark information with a uniform time standard. The time line comprises a series of pulse signals generated at selected time intervals. In a preferred embodiment, a pulse is generated every second with each 10th pulse being a long pulse. The use of a time pulse line permits the instructor to include the speed of the trainees performance on various portions of the drill among the criteria for evaluation.

Tape 86 thus contains a permanent record of the following information: the number and duration of errors made by the trainee during the exercise; the location of each error in sufficient detail to know on which segment of the exercise (between which pair of bench marks) the error occurred; the time required by the trainee to complete the overall exercise and each significant segment of the exercise. By studying this information and comparing various statistical aspects of it with predetermined standards the instructor can quickly and objectively evaluate the trainees performance and abilities.

It is to be understood that the above described arrangements are merely examples of the application of the principles of the present invention. Other embodiments will be obvious to those skilled in the art without departing from the spirit or scope of the invention.

What is claimed is:

1. Apparatus for use in conjunction with a sewing machine for training sewing machine operators and evaluating their performance comprising an exercise sheet having at least one guideline thereon defining a desired stitching path, sensing means associated with said sewing machine for sensing when said guideline is positioned at a selected location on said sewing machine and first recording means for recording a first indicia when said guideline is positioned away from said desired location.

2. Apparatus in accordance with claim 1 further 1ncluding cooperating means on said exercise sheet and said sewing machine for indicating when selected points on said guideline pass over said selected location and for recording a second indicia when said selected points pass over said selected location.

3. Apparatus in accordance with claim 1 wherein said recording means creates a time record in conjunction with said indicia.

4. Apparatus in accordance with claim 1 wherein said recording means includes an error counter for maintaining a cumulative count of the number of errors made by a trainee and for displaying said count to a supervisor.

5. Apparatus in accordance with claim 1 wherein said guideline is electro-conductive and said sensing means includes electrical contacts.

6. Apparatus in accordance with claim 1 wherein said first recording means comprises a constant rate strip recorder including marking means creating a first notation when said guideline is on said selected location and creating a second notation when said guideline is away from said selected location, said first notation being distinguishable from said second notation.

7. Apparatus in accordance with claim 2 wherein said recording means comprises a constant rate strip recorder having first marking means for creating a first notation when said guideline is on said selected location and creating a second notation when said guideline is away from said selected location, and second marking means for creating selected indicia when said selected points pass adjacent said selected location.

8. Apparatus for training and evaluating the performance of sewing machine operators comprising a sewing machine having a presser foot, at least one exercise sheet having at least one guideline thereon defining the desired location of a line of stitches, said guideline having a starting point and an end point and one or more regions simulating various stitching techniques, markings on said exercise sheet adjacent said guideline separating said regions, first sensing means associated with said presser foot for indicating whether said foot is aligned with said guideline, second sensing means for detecting said markings when said markings pass said foot, and recording means for recording a first indicia when said foot passes olf said guideline and for recording a second indicia when said foot passes over said markings.

9. Apparatus in accordance with claim 8 wherein said recording means comprises a constant rate strip recorder having a first and second stylus each with first and second marking positions, said first stylus in said first position indicating that said foot is on said guideline, said first stylus in said second position indicating that said foot is off said guideline, said second stylus in said first position indicating that said foot is adjacent one of said markings, said second stylus in said second position indicating that said foot is away from said markings.

10. Apparatus in accordance with claim 8 wherein said guidelines and said markings are electro-conductive.

References Cited UNITED STATES PATENTS 2,678,692 5/1954 Ranseen 3522 R 2,943,855 7/1960 Javna et al. 273-1 E 3,390,397 6/1968 Friedlander 35-22 R X HARLAND S. SKOGQUIST, Primary Examiner US. Cl. X.R. 3S15 

